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Singlet–triplet splittings as obtained from the X α‐scattered wave method: A theoretical analysis
Author(s) -
Bagus P. S.,
Bennett B. I.
Publication year - 1975
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560090114
Subject(s) - singlet state , excited state , atomic physics , relaxation (psychology) , physics , molecule , configuration interaction , chemistry , molecular physics , quantum mechanics , psychology , social psychology
The theoretical determination of singlet–triplet splittings of the excited states of closed‐shell molecules is discussed with emphasis on the use of the X α–scattered wave method. With this method, splittings can be computed in two independent ways. Both will have corrections due to orbital relaxation effects. The singlet–triplet splittings obtained with the X α–scattered wave method for several large organic molecules are reviewed. It is seen that the results using the two splitting formulas differ by a large amount; in fact, they differ by the magnitude of the computed splitting. We provide a criterion for choosing the results obtained with one method over the other by showing that they both give upper bounds to the best result obtainable within the framework of the model. However, because of the large differences between the two methods, the quantitative value of the splitting should be viewed with caution.